TDLAS & QF Analyzers

TDLAS & QF Analyzers

TDLAS and QF analyzers are optical gas analyzers designed for reliable online measurement of key quality and contamination parameters in process gas streams. Endress+Hauser describes TDLAS (tunable diode laser absorption spectroscopy) as using laser absorption spectroscopy to measure analyte concentrations - specifically citing H₂O, H₂S, and CO₂ - while quenched fluorescence (QF) analyzers measure oxygen from trace to percent levels. These techniques are positioned as having “revolutionized online gas analysis” for quality and process control, reducing operational costs and maximizing uptime.

The principal benefit is high-selectivity, high-speed measurement with low maintenance burden. For TDLAS, the design is described as enabling measurements with “zero contact” between the process gas sample and critical analyzer components, protecting the analyzer while enabling rapid response and reliable long-term measurements and reducing the need for recalibration and constant maintenance. QF technology is positioned as a reliable alternative for trace oxygen measurement in natural gas, avoiding common failure modes of consumable-cell approaches.

QF analyzers are specifically described as practically immune to high levels of H₂S, CO₂, and H₂O present in natural gas, which can interfere with other measurement methods. Additional stated benefits include fast, continuous real-time measurement with excellent long-term stability, no moving parts, low operational costs without consumable chemicals, and strong metrology for low ppmv measurements with high precision. These characteristics support deployment where oxygen is both a quality specification and a corrosion/safety risk driver.

Typical applications include natural gas pipelines, gas processing and LNG facilities, refineries, and petrochemical processes, where online measurement of moisture, sulfur species, CO₂, and oxygen supports custody-quality gas, contamination prevention, dehydration and sweetening optimization, and protection of downstream catalysts and equipment. Because measurements are fast and continuous, the analyzers can be used to detect transient breakthrough events that periodic lab sampling may miss, improving control stability and reducing off-spec exposure windows.

Implementation priorities include selecting the appropriate optical method for the target analyte and matrix, defining sample interface strategy (in-line/extractive depending on installation), and aligning validation practices to quality requirements. With optical methods designed to reduce consumables and maintenance while preserving response speed, TDLAS and QF analyzers provide a strong foundation for continuous gas quality assurance and operational risk reduction across high-value gas infrastructure.

Forberg Smith, an exclusive authorized representative of sales and service for Endress+Hauser.